1. Field of the Invention
The present invention relates to a technique of manufacturing an exhaust gas-purifying catalyst.
2. Description of the Related Art
An exhaust gas-purifying catalyst includes, for example, a monolith substrate having through-holes therein and a catalytic layer formed on the monolith substrate. Such an exhaust gas-purifying catalyst can be obtained by, for example, coating the monolith substrate with slurry containing a raw material of the catalytic layer and subsequently subjecting the coated layer to drying and firing treatments.
In recent years, used widely are exhaust gas-purifying catalysts in which two catalytic layers having different compositions are formed on upstream and downstream sections of the monolith substrate. An example of such exhaust gas-purifying catalysts is described in Jpn. Pat. Appln. KOKAI Publication No. 2007-330879. When manufacturing this type of exhaust gas-purifying catalysts, two areas of the substrate are coated with different slurries each containing either of the raw materials of the catalytic layers.